Description: <a id="{8ABDFBD8-270C-4270-9A5B-EBF2DE83D01E}" href="https://edg.epa.gov/metadata/catalog/search/resource/details.page?uuid=%7B8ABDFBD8-270C-4270-9A5B-EBF2DE83D01E%7D">Full Metadata</a> This map service group layer displays Particulate Matter (PM2.5) data from separate sources. The first source is the USEPA's NonAttainment areas using the 2006 24-hour Standard of 35 ug/m3. The data for these polygon areas are described in the USEPA's Green Book (http://www.epa.gov/airquality/greenbook/rindex.html). The second source is a combined effort between the USEPA and the Center for Disease Control. The Center of Disease Control's (CDC) Environmental Public Health Tracking (EPHT) datawas averaged over three years ( 2004 - 2006). The USEPA's ORD calculated a three year average (2004 - 2006) using the values for PM2.5 (annual ambient concentration). These data were extracted by the CDC from the USEPA's ambient air monitors and are displayed at the county level. USEPA received the Monitor and Modeled data from the CDC and calculated the three year average displayed in the web service. For more details about the CDC EPHT data, please refer to the CDC EPHT web page (http://ephtracking.cdc.gov/showHome.action).